package org.apache.lucene.search;

/**
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.IOException;
import org.apache.lucene.index.*;

final class PhrasePositions {
    int doc; // current doc
    int position; // position in doc
    int count; // remaining pos in this doc
    int offset; // position in phrase
    TermPositions tp; // stream of positions
    PhrasePositions next; // used to make lists

    PhrasePositions(TermPositions t, int o) {
        tp = t;
        offset = o;
    }

    final boolean next() throws IOException { // increments to next doc
        if (!tp.next()) {
            tp.close(); // close stream
            doc = Integer.MAX_VALUE; // sentinel value
            return false;
        }
        doc = tp.doc();
        position = 0;
        return true;
    }

    final boolean skipTo(int target) throws IOException {
        if (!tp.skipTo(target)) {
            tp.close(); // close stream
            doc = Integer.MAX_VALUE; // sentinel value
            return false;
        }
        doc = tp.doc();
        position = 0;
        return true;
    }

    final void firstPosition() throws IOException {
        count = tp.freq(); // read first pos
        nextPosition();
    }

    final boolean nextPosition() throws IOException {
        if (count-- > 0) { // read subsequent pos's
            position = tp.nextPosition() - offset;
            return true;
        } else
            return false;
    }
}
